Industrial robot

ABSTRACT

The industrial robot has cables routed, through cable-passing holes ( 4   a,    4   b ) formed in a side of an arm, between the outside and the inside of the arm. The cables contain mold guide ( 7 ) disposed inside cable-passing holes ( 4   a   , 4   b ); cable bundle ( 6 ) that passes through the inside of mold guide ( 7 ); and filler resin ( 8 ) applied to the inside of mold guide ( 7 ). The inside of mold guide ( 7 ) is filled with filler resin ( 8 ), so that cable bundle ( 6 ) is held in place.

TECHNICAL FIELD

The present invention relates to an industrial robot, particularly,relates to a dust- and water-proof structure of cables disposed at ajoint section of an arm.

BACKGROUND ART

As a prior patent, for example, Japanese Patent Unexamined PublicationNo. H11-254377 discloses a dust- and water-proof structure of a jointsection of a robotic arm. According to the structure, cables aredisposed through a through-hole formed in the center of a joint section,and an opening of the arm is closed with a cover or a gasket.

FIG. 4 is a section view illustrating the structure of the robotdisclosed in the patent above. In robot 11 of FIG. 4, arm 16 isconnected to the upper section of arm 13 through joint J2. Havingreducer 17, joint J2 moves arm 16 with the drive of motor 18. Wiring(cables) 43 passes through the interior (through-hole) of hollow shaft28 of reducer 17. Oil seal 44 is provided to bearing 33 that is disposedon the outermost periphery of reducer 17.

According to the prior art, forming each joint so as to be the same asthe structure of joint J2 described above allows robot 11 to have dust-and water-proof joint sections.

In the conventional structure, however, drive motor 18 has to bedisposed away from the center of the joint shaft because thethrough-hole for passing through cables 43 is disposed coaxially withthe joint shaft. This positional constraint inevitably increases powertransmission components in number, such as pulley 30 and timing belt 31,and bearing parts, resulting in an oversize, overweight joint sectionwith a complicated structure.

When cables 43 cannot pass through the through-hole of reducer 17 due toincrease in number of cables, it becomes necessary to employ alarge-sized reducer having a larger through-hole, and accordingly, othercomponents including a pulley and a motor have to be larger. Thisinvites increase in size and weight of the joint section. In a robothaving such an overweight joint section, the heavy weight acts as a loadon the robot, deteriorating movements of the robot.

SUMMARY OF THE INVENTION

The industrial robot of the present invention contains a cable-passinghole formed in a side of an arm; and cables disposed inside and outsidethe arm through the hole. The cables further contain a mold guide thatis disposed inside the cable-passing hole; a bundle of cables run insidethe mold guide; and filler resin that is applied to the inner side ofthe mold guide. The inner side of the mold guide is filled with thefiller resin, by which the cable bundle is fixed.

Applying dust- and water-proof treatments to only an area having thecable-passing hole allows a joint section to not only have acost-reduced and compact structure, but also to be dust- and water-resistant.

Even when cables or fluid tubes for supplying air and gas are changed inquantity or size according to changes in specifications of, for example,a motor for driving each joint shaft of the robot, a welding feedingdevice, and various sensors mounted on the robot, the aforementionedstructure can cope with the changes easily, with no effect on the powertransmission components disposed on a joint shaft.

According to the industrial robot of the present invention, as describedabove, a dust- and water-proof structure of a joint of the arm can berealized by using a simple structure. Besides, the structure highlyadaptable to changes in cables, fluid tubes, or the like, with no needfor geometrical changes in power transmission components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the industrial robot of an exemplaryembodiment of the present invention.

FIG. 2 is a perspective view of the structure of cables employed for therobot shown in FIG. 1.

FIG. 3 is a section view of the cables in the vicinity of acable-passing hole in the robot of FIG. 1.

FIG. 4 is a section view of a structure of a conventional robot.

REFERENCE MARKS IN THE DRAWINGS

-   1 first arm-   2 second arm-   3 third arm-   4 b cable-passing hole-   5 cable guide tube-   6 cable bundle-   7 mold guide-   8 filler resin-   9 sealant-   10 cables

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an exemplary embodiment of the present invention isdescribed with reference to FIG. 1 through FIG. 3. FIG. 1 is aperspective view of a robot of the embodiment of the present invention.

The robot of FIG. 1 has first arm 1, second arm 2, third arm 3, andcable-passing holes 4 a, 4 b each of which is formed in a side adjacentto an arm joint section. Cable guide tube 5, which is disposed along theside of second arm 2, accommodates cable bundle 6 therein. Cable bundle6 contains electrical cables and gas tubes that are connected tocorresponding devices in the robot through cable-passing holes 4 a and 4b. That is, as shown in FIG. 1, cable guide tube 5 is passed throughcable-passing holes 4 a and 4 b and routed from first arm 1 throughthird arm 3. Cable guide tube 5, which is made of, for example, ametallic spring, protects cable bundle 6.

FIG. 2 is a perspective view of the structure of the cables in the robotshown in FIG. 1. FIG. 3 is a section view of the cables in the vicinityof a cable-passing hole.

Cable 10 shown in FIG. 2 contains mold guide 7 located insidecable-passing holes 4 a, 4 b in FIG. 1; cable bundle 6 of a plurality offilaments that runs inside mold guide 7; and filler resin 8 applied tothe inside of mold guide 7. Cable guide tube 5 protects cable bundle 6.Cable guide tube 5 is connected to mold guide 7.

Cable bundle 6 is disposed inside cable guide tube 5 and mold guide 7.Mold guide 7 is, for example, made of resin. The inside of mold guide 7is filled with filler resin 8 so as to fix cable bundle 6. For example,epoxy resin is employed for filler resin 8.

Mold guide 7 is, as shown in FIG. 3, disposed at each inside ofcable-passing holes 4 a, 4 b. Sealant 9 seals a gap between the outside(the outer perimeter) of mold guide 7 and the inside (the innerperimeter) of cable-passing holes 4 a, 4 b. As for sealant 9, a solidgasket typified by an O-ring is employed. Instead of an O-ring, oilseal, a V-ring, and liquid surface sealant can be employed.

In the aforementioned structure, a molded section (specifically, fillerresin 8 and sealant 9) disposed only at mold guide 7 disposed incable-passing holes 4 a, 4 b prevents the entry of dirt and water fromthe outside to the inside of the arm. That is, the structure aboveallows the internal cavities of first arm 1 having cable-passing hole 4a and of third arm 3 having cable-passing hole 4 b to be dust- andwater-resistant.

Suppose that the structure does not contain mold guide 7. With cablebundle 6 alone, since the bundle itself cannot retain a definite shape,dust or water easily enters through the gap between the bundle andcable-passing holes 4 a, 4 b. However, as described above, the structureof the embodiment contains mold guide 7 with a tube-like shape foraccommodating cable bundle 6 therein, and the gap between mold guide 7and cable bundle 6 is filled with resin, which gives mold guide 7 adefinite outer shape. By determining the shape of cable-passing holes 4a, 4 b suitable for the shape of mold guide 7, and then disposing thecable bundle so that mold guide 7 is positioned at cable-passing holes 4a, 4 b, the dust- and water-proof structure is easily obtained.

Even when cable bundle 6 has changes in numbers or types of thefilament, the dust- and water-proof structure obtained by cable-passingholes 4 a, 4 b and mold guide 7 is insusceptible to the changes, as longas the outer shape of cable bundle 6 is smaller than the inner diameterof mold guide 7. It is therefore no need for changing the size ofcable-passing holes 4 a, 4 b, and also no effect on the powertransmission components disposed on a joint shaft.

Further, suppose that cable bundle 6 is too large to be passed throughmold guide 7 because of increase in numbers or sizes of the filamentsaccording to changes in specifications for cable bundle 6. Even in sucha case, disposing another mold guide suitable for cable bundle 6 andforming cable-passing holes 4 a, 4 b so as to have a shape suitable forthe mold guide can deal with the changes. Unlike in a conventionalrobot, in this case, too, there is no effect on the power transmissioncomponents disposed on a joint shaft. In this way, with the structure ofthe embodiment, dust- and water-resistance can be easily obtained.

The simple procedures described above—forming mold guide 7 having afixed inner cavity and outer shape; passing cable bundle 6 through moldguide 7 and fixing the bundle by molding; and applying a sealing processon the outside of mold guide 7—allow the cables, which are routed fromthe outside to the inside of the robot, to be dust- and water-resistant.

The dust- and water-proof structure of a conventional robot, asdescribed in Background Art, invites a large-sized, heavyweight jointsection. In contrast, the structure of the present invention has noworry about the inconveniency, and therefore no ill effect on movementperformance of a robot.

Although the embodiment of the present invention employs cable bundle 6formed of a plurality of filaments, it is not limited thereto. Cablebundle 6 does not necessarily contain a fixed number of filaments:either one or more.

Although the embodiment shows an example where cable-passing holes 4 a,4 b are formed into a substantially round-shape, it is not limitedthereto. The holes can be formed into a substantially oval-shape, or asimilar shape.

INDUSTRIAL APPLICABILITY

The present invention provides a simply configured dust- and water-proofstructure of a robot arm, which is therefore widely applicable toindustrial robots.

1. An industrial robot comprising: a cable-passing hole formed in a sideof an arm; and cables routed between an inside and an outside of the armthrough the cable-passing hole, the cables further including: acylindrical mold guide disposed in an inside of the cable-passing hole;a cable bundle passed through an inside of the mold guide; and fillerresin applied to the inside of the mold guide, wherein, the mold guideis disposed with a length out of an entire length of the cables, on anouter perimeter of the cable bundle, and a region that is inside moldguide and adjacent to the cable-passing hole is filled with the fillerresin applied in a direction substantially orthogonal to a direction inwhich the cable bundle runs, so that the cable bundle is retained by theresin filler.
 2. The industrial robot of claim 1 further includes asealant for sealing a gap between the cable-passing hole and the moldguide.
 3. The industrial robot of claim 2, wherein the sealant is asolid gasket.
 4. The industrial robot of claim 3, wherein the solidgasket is an O-ring.
 5. The industrial robot of claim 1, wherein thecable-passing hole is formed in a vicinity of a joint section of thearm.
 6. The industrial robot of claim 1, wherein the filler resin isepoxy resin.